Rhodamine-based multianalyte colorimetric probe with potentialities as on-site assay kit and in biological systems

Herein, we report a new rhodamine-based multianalyte (Cu2+ and Hg2+) fluorescent sensor RH-FP. The synthesized probe acts as a dual chemosensor for recognition of Cu2+ and Hg2+ in acetonitrile-water( 4:1 v/v, pH 7.2 with 10 mM, HEPES) in the presence of other miscellaneous metal cations i.e. Ag+, Al3+, Ba2+, Ca2+, Cd2+, Fe3+, Fe2+, K+, Li+, Mg2+, Mn2+, Cu+2, Pb2+, Ni2+, Na+ and Zn2+. A highly selective and sensitive colorimetric (colorless to pink) response accompanied by a significant increase in absorption and emission maxima (250-folds) was observed by the interaction of RH-FP and Cu2+ or Hg2+. This makes RH-FP a suitable bare-eye detector. The Job's plot and ESI-MS confirm 1:1 binding stoichiometry between-sensor RH-FP and metal cations. The calculated binding constant for the complexes (RH-FP-Cu2+ and RH-FP-Hg2+) are 3.37 x 10(5) mol(-1) and 7.6 x 10(5) mol(-1), with a detection limit of 3.9 nm and 2.36 nm respectively. The binding mechanism was confirmed by Fourier transform infra-red spectroscopy (FT-IR) H-1, C-13 NMR and density functional theory (DFT) calculations. Moreover, the fluorescent sensor RH-FP displayed potential in-field applications as detection kit and in fluorescent imaging of biological systems to detect Cu2+ or Hg2+. (c) 2017 Elsevier B.V. All rights reserved.